Hemodialysis performance and anticoagulant activities of PVP-k25 and carboxylic-multiwall nanotube composite blended Polyethersulfone membrane

Dialysis treatment, in vitro, and anticoagulation activity of polysulfone-polyacrylamide based-blend membranes: an experimental study

The majority of treatments are performed with polysulfone (PSf) membranes. The main issue of the PSf membrane is its lack of endothelial function, leading to various processes like platelet adhesion, protein adsorption, and thrombus formation when comes in contact with blood. The crucial aspect in the development of hemodialysis (HD) membrane materials is a biocompatibility factor. This study aims to improve the performance and biocompatibility of PSf membranes by utilizing polyethylene glycol (PEG) as a pore-forming agent and polyacrylamide (PAA) as a multifunctional modifying additive owing to its non-toxic, and biocompatible nature. The formulated HD membranes were characterized using Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and Water Contact Angle (WCA) measurements. The biocompatibility results showed that PSf-PAA membranes reduced the adsorption of bovine serum albumin (BSA) protein, hemolysis process, thrombus formation, and platelets adhesion with improved in vitro cytotoxicity results as well as anticoagulation performance. The protein separation results showed that PSf-PAA membranes were able to reject 90.1% and 92.8% of BSA protein. The membranes also showed better uremic waste clearance for urea (76.56% and 78.24%) and creatinine (73.71% and 79.13%) solutes, respectively. It is conceivable that these modern-age membranes may surpass conventional HD membranes regarding both efficiency and effectiveness.

Preparation and Hemocompatibility of Novel Antioxidant-Modified Polyethersulfone Membranes as Red Blood Cell Thrombosis Inhibitors

The contact between the dialysis membrane and blood can induce oxidative stress and thrombosis, causing oxidative organ damage and impaired toxin clearance. To date, the selection of anticoagulants has focused on mechanisms inhibiting white, but not red (erythrocytes) thrombus formation. In the present study, polyethersulfone (PES) membranes are modified with the antioxidant drug tiopronin; the physicochemical properties and dialysis performance of the Tio-PES membranes are evaluated. The effects on erythrocyte thrombosis are evaluated in terms of erythrocyte morphology, prothrombotic properties (adhesion, aggregation, viscosity, sedimentation, and hemolysis), and fibrinogen (FIB)-erythrocyte interactions. The regular anticoagulant and antiplatelet properties are also assessed. Superoxide dismutase, malondialdehyde, plasma protein, and complement C3a are further determined. Finally, the biosafety of the Tio-PES membranes is evaluated both in vitro and in vivo. The Tio-PES membranes exhibit excellent physicochemical properties and improved dialysis performance. It is found that the Tio-PES membranes stabilize erythrocyte morphology, reduce erythrocyte prothrombotic properties, decrease FIB adsorption, and prevent red thrombus formation. In addition, the Tio-PES membranes exhibit excellent antioxidant properties and show biosafety in primary toxicity studies. Thus, Tio-PES membranes hold promise as novel, safe, and effective dialysis materials for potential clinical application.

High-performance sulfonated polyether sulfone/chitosan membrane on creatinine transport improved by lithium chloride

Membrane-based polyether sulfone (PES) is a potential candidate for hemodialysis because of its properties such as high mechanical strength, thermal stability, and chemical resistance. However, the nature of the hydrophobicity in the PES membrane inhibits their performance in transporting creatinine. In this study, polyethersulfone (PES) membranes were modified using a sulfonation process and the addition of chitosan (CS) and lithium chloride (LiCl) to improve its performance in transporting creatinine. The FTIR spectrum of the modified membrane shows peaks of the sulfonate (-SO2), amine (NH), and hydroxyl (-OH) groups in absorption areas of 1065 cm-1, 1650 cm-1, and 3384 cm-1, respectively, indicating that the membrane SPES/CS-LiCl has been successfully prepared. The modified PES membranes shows a higher porosity, swelling, water absorption, and hydrophilicity than pure PES membrane. The modification of the PES membrane in this study also enhances the ability of the membrane to transport creatinine. In the pure PES membrane, the creatinine clearance is 0.30 mg/dL, while in the SPES/CS-LiCl (5:2) membrane the creatinine clearance is 0.42 mg/dL.

Artificial intelligence application in adsorption of uremic toxins: Towards the eco-friendly design of highly efficient with potential applications as hemodialysis membranes

Six Functionalized Activated Carbon Cloths (FACCs) were designed to obtain fundamental information for training a Bayesian Regularized Artificial Neural Network (BRANN) capable of predicting adsorption capacity of the FACCs to synthesize tailor-made materials with potential application as dialysis membranes. Characterization studies showed that FACCs have a high surface area (1354-2073 m2 g-1) associated with increased microporosity (W0, average: 0.57 cm3 g-1). Materials are carbonaceous, with a carbon content between 69 and 92%. Chemical treatments modify the pHpzc of materials between 4.1 and 7.8 due to incorporating functional groups on the surface (C=O, -COOH, -OH, -NH, -NH2). Uremic toxins tests showed a high elimination rate of p-cresol (73 mg g-1) and creatinine (90 mg g-1) which is not affected by the matrix (aqueous solution and simulated serum). However, in the case of uric acid, adsorption capacity decreased from 143 mg g-1 to 71 mg g-1, respectively. When comparing the kinetic constants of the adsorption studies in simulated serum versus the studies in aqueous solution, it can be seen that this does not undergo significant changes (0.02 min-1), evidencing the versatility of the material to work in different matrices. The previous studies, in combination with characterization of the materials, allowed to establish the adsorption mechanism. Thus, it permitted to train the BRANN to obtain mathematical models capable to predict the kinetic adsorption of the toxins studied. It is concluded that the predominant adsorption mechanism is due to π-π interactions between the adsorbate unsaturations with the material's pseudo-graphitic planes. Results show that FACCs are promising materials for hemodialysis membranes. Finally, taking into consideration the adsorption capacities and rates, as well as the semiquantitative analysis of the environmental impact associated with the preparation of the adsorbents, the best adsorbent (CC, Eco-Scale = 91.5) was selected. The studies presented show that the material is eco-friendly and highly efficient in the elimination of uremic toxins.

Crown ether-functionalized cellulose acetate membranes with potential applications in osseointegration

Due to its inherent properties and wide availability, cellulose acetate is an extremely competitive candidate for the production of polymeric membranes. However, for best results in particular applications, membrane modification is required in order to minimize unwanted interactions and introduce novel characteristics to the pristine polymer. In this study, the surface of commercial cellulose acetate membranes was functionalized with 4'-aminobenzo-15-crown-5 ether, using a covalent bonding approach. The main goal was the improvement of the membranes biomineralization ability, thus making them prospective materials for bone regeneration applications. The proposed reaction mechanism was confirmed by XPS and NMR analysis while the presence of the functionalization agents in the membranes structure was showed by ATR FT-IR and Raman spectra. The effects of the functionalization process on the morphology, thermal and mechanical properties of the membranes were studied by SEM, TGA and tensile tests. The obtained results revealed that the cellulose acetate membranes were successfully functionalized with crown ether and provided a good understanding of the interactions that took place between the polymer and the functionalization agents. Moreover, promising results were obtained during the Taguchi biomineralization studies. SEM images, EDX mapping and XRD spectra indicating that the CA-AB15C5 membranes have a superior Ca²⁺ ions retention ability, this causing an accentuated calcium phosphate deposition on the modified polymeric fibers, compared to the neat CA membrane.

Dual Optimized Sulfonated Polyethersulfone and Functionalized Multiwall Carbon Tube Based Composites High Fouling Resistance Membrane for Protein Separation

Commercial grade sulfonated-Polyethersulfone (S-PES) and functionalized multiwall carbon nanotube (f-MWCNT)/polyvinylpyrrolidone (PVP) nanocomposites (NCs) were used to enhance and optimize the antifouling, protein resistance and protein separation properties of the S-PES ultrafiltration membranes. The polarities of sulfonic groups of S-PES, carbonyl carbon of pyrrolidone, hydroxyl and carboxyl groups of f-MWCNT in the membrane composition helped to strongly bind each other through hydrogen bonding, as shown by Fourier-transform infrared spectroscopy (FTIR). These binding forces greatly reduced the leaching of NCs and developed long finger-like projection, as confirmed by elution ratio and cross-sectional studies of the membranes via field emission scanning electron microscope (FESEM). The contact angle was reduced up to 48% more than pristine PES. Atomic force microscopy (AFM) was employed to study the various parameters of surface roughness with 3d diagrams, while grain analysis of membrane surface provided a quantitative estimation about volume, area, perimeter, length, radius and diameter. The NCs/S-PES enhanced the flux rate with an impressive (80–84%) flux recovery ratio and (58–62%) reversible resistance (R_r) value in situ, with 60% and 54.4% lesser dynamic and static protein adsorption. The best performing membrane were reported to remove 31.8%, 66.3%, 83.6% and 99.9% for lysozyme-(14.6 kDa), trypsin-(20 kDa), pepsin-(34.6 kDa) and bovine serum albumin (BSA-66 kDa), respectively.

Effect of Dope Flow Rate and Post-Treatment on the Morphology, Permeation and Metal Ion Rejection from PES/LiBr-Based UF Hollow Fiber Membranes

This study investigated the influence of dope extrusion rate (DER) and post-treatment effect on the morphology, permeation, and metal ion rejection by polyethersulfone/lithium bromide (PES/LiBr)-based hollow fiber (HF) membranes. HF fibers were spun with 2.25, 2.5, and 3.1 ratios of DER to bore fluid rate (BFR), wherein DER varied from 11.35, 12.5, to 15.6 mL/min with a fixed BFR (5 mL/min). Molecular weight cutoff (MWCO), pore size, water flux, and flux recovery ratio were determined, whereas lake water was used to observe the rejection rate of dissolved metallic ions. Results showed that with the increase of the DER wall thickness (WT), HFs increased from 401.5 to 419.5 um, and furthermore by the post-treatments up to 548.2 um, as confirmed by field emission scanning electron microscope (FESEM) analysis. Moreover, MWCO, pore size, and the pure water permeation (PWP) of the HF membranes decreased, while the separation performance for polyethylene glycol (PEG) solute increased with increasing DER. Post-treated HFs from 11.35 mL/min of DER showed 93.8% of MWCO value with up to 90% and 70% rejection of the arsenic and chromium metallic ions, respectively, in comparison with all other formulated HFs.

Fabrication and dialysis performance of functionalized multiwall carbon nanotubes integrated cellulose acetate/poly(vinylpyrrolidone) membranes

Mixed matrix membranes (MMMs) of cellulose acetate/poly(vinylpyrrolidone) (CA/PVP) infused with acid functionalized multiwall carbon nanotubes (f-MWCNTs) were fabricated by an immersion phase separation technique for hemodialysis application. Membranes were characterized using FTIR, water uptake, contact angle, TGA, DMA and SEM analysis. The FTIR was used to confirm the bonding interaction between CA/PVP membrane matrix and f-MWCNTs. Upon addition of f-MWCNTs, TGA thermograms and glass transition temperature indicated improved thermal stability of MMMs. The surface morphological analysis demonstrated revealed uniform distribution of f-MWCNTs and asymmetric membrane structure. The water uptake and contact angle confirmed that hydrophilicity was increased after incorporation of f-MWCNTs. The membranes demonstrated enhancement in water permeate flux, bovine serum albumin (BSA) rejection with the infusion of f-MWCNTs; whereas BSA based anti-fouling analysis using flux recovery ratio test shown up to 8.4% improvement. The urea and creatinine clearance performance of MMMs were evaluated by dialysis experiment. It has been found that f-MWCNTs integrated membranes demonstrated the higher urea and creatinine clearance with increase of 12.6% and 10.5% in comparison to the neat CA/PVP membrane. Thus, the prepared CA/PVP membranes embedded with f-MWCNTs can be employed for wide range of dialysis applications.

Case studies of clinical hemodialysis membranes: influences of membrane morphology and biocompatibility on uremic blood-membrane interactions and inflammatory biomarkers

End stage renal disease (ESRD) patients depend on hemodialysis (HD) as a life-sustaining treatment, but HD membrane properties play a critical role in blood activation during HD and can lead to severe patient outcomes. This study reports on a series of investigations on the common clinical HD membranes available in Canadian hospitals to explore the key reasons behind their susceptibility to blood activation and unstable cytokine. Clinical HD membranes composed of cellulose triacetate (CTA) and polyvinylpyrrolidone: polyarylethersulfone (PAES: PVP) were thoroughly characterized in terms of morphology and chemical composition. Membrane-surface interactions with uremic blood samples after HD treatment were probed using Fourier Transform Infra-Red (FTIR) and Raman spectroscopic techniques in order to understand changes in chemistry on membrane fibers. In addition, as part of this innovative study, we utilized Molecular Modeling Docking to examine the interactions of human blood proteins and membrane models to gain an in-depth understanding of functional group types responsible for perceived interactions. In-vitro adsorption of fibrinogen on different clinical HD membranes was compared at similar clinical operating conditions. Samples were collected from dialysis patients to ascertain the extent of inflammatory biomarkers released, before, during (30 and 90 min) and after dialysis (4 h). Collected blood samples were analyzed using Luminex assays for the inflammatory biomarkers of Serpin/Antithrombin-III, Properdin, C5a, 1L-1α, 1L-1β, TNF-α, IL6, and vWF. We have likewise incubated uremic blood in vitro with the two membrane materials to determine the impact that membrane materials pose in favor of activation away from the hydrodynamics influences. The results of our morphological, chemical, spectroscopic, and in vitro incubation analyses indicate that CTA membranes have a smoother surface and higher biocompatibility than PAES: PVP membranes, however, it has smaller pore size distribution, which results in poor clearance of a broad spectrum of uremic toxins. However, the rougher surface and greater hydrophilicity of PAES: PVP membranes increases red blood cell rupture at the membrane surface, which promotes protein adsorption and biochemical cascade reactions. Molecular docking studies indicate sulfone functional groups play an important role in the adsorption of proteins and receptors. PAES: PVP membranes result in slower but greater adsorption of fibrinogen, but are more likely to experience reversible and irreversible fouling as well as backfiltration. Our major finding is that a single dialysis session, even with a more biocompatible membrane such as CTA, increases the levels of complement and inflammation factors, but to a milder extent than dialysis with a PAES membrane.